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Zhejiang Yihong stainless steel pipeline equipment Co., Ltd! EN

Stainless steel steel Seamless pipe manufacturing process   


1、 Process control:

1) Starting process:

In the beginning, we should master the principle of "one strictness, two diligence and three quickness", and strictly control the heating temperature at 1000-1100 between; Frequent feeding, only in furnace 8~12 The branch steel pipe is heated to prevent heat penetration or over burning; Turn frequently to prevent the internal and external surfaces of steel pipes in the furnace, i.e. one side is not thoroughly heated and the other side is overheated; Heat up quickly. First heat the furnace to nine hundred and fifty The steel pipes above ℃ can be heated in the furnace. It is strictly forbidden to install the furnace in cold condition and add fuel when there are steel pipes in the furnace; Fast start: that is to say, the starting speed should be fast; Quick cooling: cooling in the pool immediately after finishing.

two )Pickling and degreasing process:

To achieve five No: no acid, no acid, no oil, no lime, no residual acid;

First add a certain amount of water into the cleaned acid tank, and then prepare it according to the table below

Solution name








During operation, it should be handled with care to prevent the steel pipe from being scratched and bent. The thin-walled pipe should be placed on the upper part of the acid cylinder to prevent extrusion deformation;

After pickling and degreasing, the steel pipe shall be lifted into the clean water tank immediately and vibrated up and down. After shaking off the oxide skin on the steel pipe surface, the steel pipe shall be lifted out of the water tank and washed with high-pressure water;

3) Lubrication and baking process:

Lubrication is the key process of production, so we should pay attention to the quality of lubrication. According to the process requirements, brush and bake the steel pipe lubricant. Reaming pipe: first coat the inner hole, and then dry it in the furnace; two point five Empty pipe drawing: the steel pipe is heated in an advanced furnace, and then coated with external lubricant for natural drying; Wall reducing pipe: first brush the inner hole, bake in the furnace, and then coat the surface lubricant out of the furnace to dry naturally;

four Grinding working procedure

Check the inner and outer surface of the steel pipe one by one, and mark the defects such as cracks, pits, scabs, rolling and warping. The tube blanks with different specifications and steel grades shall be grinded by classification. The inner surface of the steel pipe should be polished one by one by lighting the inner hole of the steel pipe with a low-pressure portable lamp; The grinding equipment shall be used for grinding one by one. The grinding parts shall be round without edges and corners, and shall not be ground into grooves or pits. The ratio of grinding depth to width is 1: 8. The wall thickness at the grinding position shall not exceed the negative deviation.

(5) Cold drawing process:

Select and match the mold according to the technical requirements of the process card;

When drawing the wall reducing pipe, the Soviet style external mold and internal mold shall be equipped according to the requirements of the process card, and the distance between the sizing intersection point of the internal mold and the external mold shall be adjusted. The chamfering of the internal mold shall be on the intersection point of the sizing belt of the external mold and the outlet chamfer, and the advance amount shall be determined according to the steel pipe specification

Outer diameter( mm




Wall thickness( mm




Lead time( mm


The internal and external molds are basically flush

backward 1~2

According to the bright cathode width of the internal mold working zone after the first cold drawn tube is drawn, whether it is appropriate or not is determined

Outer diameter( mm




Width of working belt( mm




The upper limit is taken for the thick wall pipe and the lower limit is taken for the thin wall pipe; The upper limit for large deformation and the lower limit for small deformation;

(6) Solution treatment process:

After the furnace is ignited normally, adjust the gas pressure to normal, heat the furnace, turn on the cooling water and the furnace roll at the same time;

Steel pipes with different steel grades, heat numbers and specifications are heated in different furnaces to avoid mixed steel grades, mixed heat numbers and mixed specifications, and the steel pipes of different steel grades and specifications have different temperature requirements;

When the large-size steel pipe with wall thickness can not be cooled thoroughly, it should be lifted into the pool for cooling;

keep five Seconds later, loosen the pressure pump valve to eliminate the pressure in the steel pipe;

(7) Straightening and cutting process:

When straightening, pay attention to the quality of the steel pipe at any time to prevent the straightening roller from being too tight, so as to avoid the existence of straightening marks and hair. If it is found, the straightening roll shall be adjusted in time; When straightening thin-walled tube, if the gap between straightening rollers is too small, it will cause the steel tube to be flattened and straightened, which can be straightened twice or several times. The straightness requirements of steel pipe are as follows:


Intermediate tube

Finished pipe (mm)

Wall reducing tube

Empty tube

Straightness (mm / M)




eight )NDT:

According to the relevant process parameters of the instrument set by the standard sample tube, the perpendicularity, water layer distance and incident angle offset of the probe are adjusted repeatedly according to the artificial defects on the sample tube. The maximum reflected wave amplitude is obtained by using the artificial defects on the inner and outer walls, and the difference of sensitivity between the two is less than or equal to 2Db Adjust the alarm sensitivity to make the artificial defect reflected wave on the instrument oscillograph screen full scale 50-80% Left and right alarm;


nine )Hydrostatic test:

Start the pressure test pump to increase the water pressure in the steel pipe to the pressure required by the test;

Tighten the pressure test valve, turn off the pressure test valve switch, and keep five Second;

Loosen the steel pipe sealing device, drain the water in the steel pipe, and remove the steel pipe;


ten )Physical and chemical test:

The microscope room should be kept clean and no smoking; In the focusing distance, first make the sample close to the objective lens, then coarse adjust from near to far, and then fine adjust after approaching the focal length. two two five   If there is dirt on the mirror surface, wipe it with soft pen or degreasing feather, and then wipe it with lens paper. If necessary, it can be scrubbed with xylene;

The dimensions of the specimens are as follows:

one Group: steel pipe specification mm   Sample length mm   wide mm   thick mm   Number of samples

       five D fifteen      80~100                           two

Note: select semi tubular or navicular specimens, bend after corrosion, and their corresponding to be inspected

two Group: steel pipe specification mm   Sample length mm   wide mm   thick mm   Number of samples

         D>15         80~100             three 4mm    two

three 4mm     four

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